451 overheating, even when moving

I brought my 71 Duster home yday, and had to stop 2x to let it cool down and puke :( what is normally a 30 min drive, using the highway, took almost 3 hours while avoiding the highway

it has a 400 bored out to 451, and would get up to 230f after to 12 minutes, and it wasn't even 30c (less than 90f?)

It was a drag car and the engine is very high compression which contributes to the problem

3 core champion rad, electric fans that are always on when running, using a manual switch

Everything was flushed so there is a possibility they put too much back in the rad, what's a good level? Touching the top hose? Above the top hose?

Any suggestions to help it keep cooler are appreciated

I don't know if they replaced the t-stat, so I've ordered a high flow Mr gasket, the milodon is sold out everywhere I looked

I'm going to grab some water wetter this morning, it can't hurt, and the car is no longer drag racing anyway.

My neighbour, a retired mechanical engineer who used build race engines as a hobby, has suggested adding a big remote oil cooler to the mix with a t-stat controller.

Thanks